1. Field of Invention
The present invention relates to a microwave oven, and more particularly, to a microwave oven capable of uniformly heating an object by means of a plurality of heaters.
2. Description of the Prior Art
A general microwave oven is to heat an object by irradiating microwaves into a cavity of the microwave oven. However, a latest microwave oven has employed heaters as another heat source in addition to the microwaves in order to heat the object in a variety of fashions.
FIG. 1 shows a major portion of a conventional microwave oven. FIG. 2a shows a major portion of another conventional microwave oven. FIG. 2b is a sectional view showing the interior of a cavity of the microwave oven shown in FIG. 2a. 
As shown in FIG. 1, a main body 10 of the microwave oven is provided with a cavity 11 with an open front face as a space in which an object is heated by means of microwaves or heat of heaters. Further, a door 15 for opening and closing the cavity 11 is hingedly installed at a front plate 13 defining the front face of the main body 10.
A side of the cavity 11 in the main body 10 is provided with an electronic equipment installation chamber (not shown) in which parts for generating microwaves such as a magnetron and a high voltage transformer are installed. A control panel 17 is installed on a portion corresponding to the front of the electronic equipment installation chamber. The control panel 17 functions to receive a variety of signals for operating the microwave oven and to display a variety of information during the operation of the microwave oven.
In order to heat the object put into the cavity 11, a fixed heater 21 is installed in the cavity 11. The fixed heater 21 is mounted, for example, on a ceiling of the cavity 11 to heat a surface of the object, thereby complementing disadvantages in a microwave-heating fashion.
In addition, the conventional microwave oven shown in FIGS. 2a and 2b is provided with a pivotable heater 23, which is upward and downward pivotably installed at a rear portion of the cavity 11. That is, the pivotable heater 23, which is vertically installed adjacent to a rear surface of the cavity 11, may upward and downward pivot on its lower end through a predetermined angle according to food as an object to be cooked so that the distance between the pivotable heater 23 and the object decreases.
Therefore, radiant or convective heat from the pivotable heater 23 may be more effectively transmitted to the object to be heated in the cavity 11. In the meantime, the other constitutional elements except for the pivotable heater 23 of the microwave oven shown in FIGS. 2a and 2b are the same as the microwave oven shown in FIG. 1. Thus, like reference numerals are given to designate like other elements.
However, the conventional microwave ovens have the following problems.
As described above, the conventional microwave ovens heat the object (food) by means of the fixed heater 21 installed on the ceiling of the cavity 11 or the pivotable heater 23 installed to pivot through a predetermined angle on the lower end thereof at the rear portion of the cavity 11.
However, since the object to be cooked is seated on a lower surface of the cavity 11, a lower surface of the object cannot be heated by the fixed or pivotable heater 21 or 23. Therefore, there is a disadvantage in that the object should be inconveniently turned over in order to heat the lower surface of the object seated in the cavity 11 by using the heater 21 or 23.
In addition, the pivotable heater 23 should be pivoted upward and downward by hand or by a driving motor. In the case that the heater is pivoted by hand, there is inconvenience in that the pivotable heater 23 should be pivoted by hand whenever cooking is made using the pivotable heater 23. Furthermore, when the pivotable heater 23 is pivoted to be in a vertical state after cooking the object, a user may get burned by remaining heat caused from the pivotable heater 23.